Abstract

Douglas fir (Pseudotsuga menziesii) is one of the most important non-indigenous tree species in Germany. The species is characterized by a wide amplitude of growing conditions, and is of increasing interest, in particular from the perspective of climate change. Douglas fir is nevertheless particularly susceptible to fungal pathogens, such as Rhabdocline pseudotsugae. The aim of the present study was therefore to develop an early detection method for R. pseudotsugae based on the polymerase chain reaction (PCR). Existing molecular techniques were adapted and optimized to detect the pathogen in small sample volumes. Both healthy and infected Douglas firs were examined, with various tissue types (buds, cambial tissue, needles) and seeds tested for the presence of R. pseudotsugae. Non-infected Douglas firs did not give positive responses in the molecular analyses, but the pathogen was clearly detected in buds, cambial tissues, needles and seeds of infected trees. To date, the fungus has been considered an obligate biotrophic needle parasite. The present results provide clear evidence, however, for the existence of an endophytic stage in the life cycle of R. pseudotsugae. In contrast with previous studies, this paper investigates the dispersal of the fungus via seeds.

Keywords

Notes

Acknowledgments

We would like to express our thanks to Sachsenforst (Graupa) and Forstbotanischer Garten Tharandt for the supply of plant material and seeds. We would also like to thank Astrid Sahre and Katrin Winkler (Institute of Forest Botany and Forest Zoology, TU Dresden) for their valuable support in the laboratory. We also thank the anonymous referees for their helpful comments and for improving the manuscript. The study was financially supported by the Federal Ministry of Education and Research (BMBF—program “Biotechnology—BioChance”, project KLONFORST).

Catal, M. (2002). Development and testing of oligonucleotide probes for detection and identification of some fungal pathogens and endophytes of conifers [doctoral dissertation]. East Lansing: Department of Plant Pathology, Michigan State University.Google Scholar